Unio delphinus Spengler, 1793
Spengler, 1793. Skr. Naturhist. Selsk. 3: 63, no. 28.

Unio delphinus — Simpson (1900), Simpson (1914), Araujo et al. (2009), Khalloufi et al. (2011), IUCN (2011), ... Ma et al. (2024), Dai et al. (2025), Wu et al. (2025), Chen et al. (2025), Hou et al. (2025)
Unio pictorum delphinus — Haas (1940), Haas (1969)

Unio hispanus Rossmässler, 1844
‘Moq.-Tand. in litt.’ Rossmässler, 1844. Icon. Land- und Süssw.-Moll. 2 (6): 26, pl. 56, fig. 747.

Unio (sec. Lymnium) turtoni — Simpson (1900), Simpson (1914)
Unio requieni — Germain (1931)
Unio pictorum delphinus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009), Fauna Europaea (2012)
Unio mancus requienii — Prie (2012)

Unio dactylus Morelet, 1845
Morelet, 1845. Moll. Terr. Fluv. Portugal: 110, pl. 14, fig. 2.
(homonym of Unio dactylus Lea, 1840)
Type(s): HOLOTYPE BMNH_93-2-4-1587, Guadiana, near Castro, Portugal.

Unio (sec. Lymnium) pictorum — Simpson (1900), Simpson (1914)
Unio pictorum delphinus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009), Fauna Europaea (2012)

Unio mucidus Morelet, 1845
Morelet, 1845. Moll. Terr. Fluv. Portugal: 111, pl. 14, fig. 3.
Type(s): HOLOTYPE BMNH_92-2-4-1974, le Cavado, Portugal.

Unio (sec. Lymnium) pictorum — Simpson (1900), Simpson (1914)
Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Fauna Europaea (2012), Lopes-Lima et al. (2017), Araujo et al. (2018)
Unio pictorum — He & Zhuang (2013)

Unio hyperephanus da Silva e Castro, 1885
da Silva e Castro, 1885. Bull. Soc. Malac. France 2: 289.
Castro in Locard, 1899. Conchyliol. Portug.: 244.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio nevesi da Silva e Castro, 1885
da Silva e Castro, 1885. Bull. Soc. Malac. France 2: 290.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio simoesi da Silva e Castro, 1885
da Silva e Castro, 1885. Bull. Soc. Malac. France 2: 292.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio (hispanus var.?) sevillensis Kobelt, 1887
Kobelt, 1887. An. Soc. Españ. Hist. Nat. 16: 437.
Kobelt, 1888. Icon. Land- und Süssw.-Moll. 3: 56, pl. 89, fig. 496.
(intro'd as intra-sp. of Unio hispanus Rossmässler, 1844)

Unio pictorum delphinus — Haas (1940), Haas (1969)

Unio sousanus Locard, 1889
Drouët, 1857. Étud. Naïades. France, Unio: pl. 7, fig. 3 [as ‘Unio requienii var. acruata’].
de Joannis, 1859. Ann. Soc. Linn. Maine-et-Loire 3: 291, pl. 11, fig. 2 [as ‘Unio requienii var. acruatus’].
‘Castro’ Locard, 1889. Contr. Faune Malacol. Franc. 13: 165 [59].
‘Castro’ Locard, 1893. Coqu. Eau Douce Saumâtre France: 197, fig. 211 [as ‘souzanus’].
‘Castro’ Locard, 1899. Conchyliol. Portug.: 258.
Type(s): LECTOTYPE MNHN_22545 (by Graf, 2011: 505), le Rhône, à Valence (Drôme).

Unio (Cyrtusiana) souzanus [sic] — Germain (1904)
Unio requieni — Germain (1931)
Unio elongatulus requienii — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)
Unio mancus requienii — Prie (2012)

Unio subhispanus Locard, 1889
‘Castro’ Locard, 1889. Contr. Faune Malacol. Franc. 13: 171 [65], 253 [147].
‘Castro’ Locard, 1893. Coqu. Eau Douce Saumâtre France: 200.
‘Castro’ Locard, 1899. Conchyliol. Portug.: 244.
Type(s): LECTOTYPE MNHN_22562 (by Graf, 2011: 507), La Loire, à Saint-Gemmes, près Angers.

Unio (Hispaniana) subhispanus — Germain (1904)
Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)
Unio mancus requienii — Prie (2012)

Unio hispanus var. sphenoides Westerlund, 1892
Westerlund, 1892. An. Soc. Españ. Hist. Nat. 21: 390.
(intro'd as intra-sp. of Unio hispanus Rossmässler, 1844)

Unio pictorum delphinus — Haas (1940), Haas (1969)

Unio cameratus Drouët, 1893
Drouët, 1893. J. de Conch. 41: 169.
Drouët, 1893. Mém. Acad. Sci. Dijon 4: 183, pl. 2, fig. 8.

Unio cameratus — Kobelt (1903)
Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio decurtatus Drouët, 1893
Drouët, 1893. J. de Conch. 41: 170.
Drouët, 1893. Mém. Acad. Sci. Dijon 4: 185, pl. 1, fig. 9.

Unio decurtatus — Kobelt (1903)
Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio gravatus Drouët, 1893
Drouët, 1893. Unionidae de l’Espagne: 49.

Unio gravatus — Kobelt (1903)
Unio pictorum delphinus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio limosellus Drouët, 1893
Drouët, 1893. J. de Conch. 41: 169.
Drouët, 1893. Mém. Acad. Sci. Dijon 4: 184, pl. 12, fig. 4.

Unio limosellus — Kobelt (1903)
Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio souzanus Locard, 1893
‘Castro’ of Authors.
Locard, 1893. Coqu. Eau Douce Saumâtre France: 197.
Germain, 1904. Bull. Soc. Sci. Nat. Ouest France 4: 275 [37].
Germain, 1931. Faune de France 22: 737.
Haas, 1940. Zool. Ser. Field Mus. Nat. Hist. 24: 126.
(error for Unio sousanus Locard, 1889)

Unio abrantesianus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 253.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio allenianus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 255.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio barbozanus Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 160 [54]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 233.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio castroi Locard, 1899
Bourguignat in Locard, 1889. Contr. Faune Malacol. Franc. 13: 160 [54]. [nomen nudum]
Bourguignat in Locard, 1899. Conchyliol. Portug.: 234.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio chasmirhynchus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 246.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio chorellinus Locard, 1899
Locard, 1899. Conchyliol. Portug.: 228.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio chorellus Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 158 [52] [as ‘chlorellus’]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 227.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio cyrtus Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 165 [59]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 257.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio euchasmus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 249.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio hypoxanthus Locard, 1899
Casto in Locard, 1899. Conchyliol. Portug.: 226.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio mundanus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 247.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio neothaumus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 259.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio novus Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 165 [59]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 258.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio ocresanus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 236.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio oncomensis Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 152 [46] [as ‘oncomenus’]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 225.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio paulinoi Locard, 1899
Locard, 1899. Conchyliol. Portug.: 242.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio scalabisianus Locard, 1899
Castro in Locard, 1899. Conchyliol. Portug.: 254.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio schousboei Locard, 1899
Bourguignat in Locard, 1899. Conchyliol. Portug.: 250.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio silvai Locard, 1899
Bourguignat in Locard, 1899. Conchyliol. Portug.: 235.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio submucidus Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 160 [54]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 230.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio taganus Locard, 1899
Servain in Locard, 1899. Conchyliol. Portug.: 252.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio tameganus Locard, 1899
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 146 [40]. [nomen nudum]
Castro in Locard, 1899. Conchyliol. Portug.: 221.

Unio pictorum mucidus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio requienii taginus Kobelt, 1903
Kobelt, 1903. Icon. Land- und Süssw.-Moll. 10: 28, pl. 280, fig. 1796.
(intro'd as intra-sp. of Unio requienii Michaud, 1831; homonym of Unio littoralis taginus Kobelt, 1903)

Unio requienii taginus — Kobelt (1903)
Unio pictorum delphinus — Haas (1940), Haas (1969)
Unio delphinus — Araujo et al. (2009)

Unio subhispanicus Germain, 1931
‘Castro in Locard’ of Authors.
Germain, 1931. Faune de France 22: 737.
Prie, 2012. MalaCo 8: 432.
(error for Unio subhispanus Locard, 1889)

Unio requieni — Germain (1931)

Unio hispanicus Graëls, 1846
Graëls, 1846. Catal. Moll. Esp.: 22.
‘Moquin. Rossm.’ Lea, 1852. Synopsis Fam. Naiades: 30.
‘Moquin. Rossm.’ Lea, 1870. Synopsis Fam. Naiades: 48.
(error for Unio hispanus Rossmässler, 1844)

Unio requienii var. arcuata Drouët, 1857
Drouët, 1857. Étud. Naïades. France, Unio: pl. 7, fig. 3.
de Joannis, 1859. Ann. Soc. Linn. Maine-et-Loire 3: 291, pl. 11, fig. 2.
(misidentified reference to Unio arcuata Jacquemin, 1835)

Unio (Cyrtusiana) souzanus [sic] — Germain (1904)
Unio requieni — Germain (1931)

Unio hispanus Lowe, 1860
Lowe, 1860. unknown publication: 176.
(reference to Unio hispanus Rossmässler, 1844)

Unio elongatulus durieui — Daget (1998)

Unio chlorellus Locard, 1889
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 158 [52].
(error for Unio chorellus Locard, 1899)

Unio oncomenus Locard, 1889
Castro in Locard, 1889. Contr. Faune Malacol. Franc. 13: 152 [46].
(error for Unio oncomensis Locard, 1899)